I’ve thought about how we say “bad guy”, when we refer to a character in a game or a story, with a different cadence than we say “bad guy”, when we mean “a guy who is bad”.
“Bad guy” in the former sense is almost its own word, with its own meaning and pronunciation.
Possible other examples:
Hot dog Black belt Lazy eye Green card
Is there a term for this phenomenon? If I could describe it, it’s when two words become a unit as opposed to discrete words.
“… with a different cadence […] with its own meaning and pronunciation.” –OP
I am interpreting that to mean stress, or intonation.
In speech, Compounds are indicated by putting the stress on the first word. A simple adjective + noun collocation has the stress on the second word.
“go left at the ‘white house'”
…may have 2 or more interpretations when you are riding down Pennsylvania avenue in Washington and talking to your driver.
For lack of a better term (at the moment), I would call it “contrastive patterns“. Possibly it is a type of “minimal pairs”.
This is a form of “coding”, which in this case means the compound noun is expected to be understood by the position of the stress. This type of production can be a source of confusion for many non-native speakers as it depends upon the de-coding of the pronunciation. Sometimes there is an L1-L2 confusion.
…such contrastive patterns as ˈHOT ˌdog(type of food) [compound] vs. ˌhot ˈDOG(hot canine)[phrase]”and “a ˈGREEN ˌhouse(a building made of glass for growing plants inside) [compound] vs. a ˌgreen ˈHOUSE(a house which is painted green) [phrase]the difference in the stress placement is a clear indication of meaning changes expressed.Compounds have primary stress on the first word and on those following them they have secondary stress. In the compound ˈGOLF ˌball, the first word has primary stress and the following the secondary stress.As for phrases, however, their qualified elements i.e. the words second in line are stressed more prominently
Spoken compounds are easily understood by native speakers, but often mis-understood by non-native speakers. This is considered a high-level topic for EFL/ESL students studying at call-centers.